Cavitation plates

A friend of mine who has quite a bit of marine knowledge suggested I put cavitation plates on the back of my boat. He claims it will be faster and smoother in rough water. The boat is a 1977 Rogers Super Cyclone 18. Any thoughts or comments on this.

I'm not an expert but I have cavitation plates on my boat now. I had a 18 foot flat bottom without cavitation plates. The cavitation plates definitely help me get on plane alot faster. However I don't think they have anything to do with making the boat faster. In order to achieve speed in my opinion you need HP.

I'm not an expert but I have cavitation plates on my boat now. I had a 18 foot flat bottom without cavitation plates. The cavitation plates definitely help me get on plane alot faster. However I don't think they have anything to do with making the boat faster. In order to achieve speed in my opinion you need HP.

with the cav plates you will be able to control the attitude and plane of the boat, more boat in the water less speed, less boat in the water more speed

Are you talking about installing the small fixed plate type cav plates or full width plates with a dozen turn buckles to adjust?

Logged

Boat #1: '77 Hondo Pantera GT Jet

"Racing is life! Anything that happens before or after, is just waiting" Steve McQueen

The problem with America is stupidity. I'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself?

For adjusting your ride attitude (bow high or low) at speed an adjustable nozzle will work the best and cost a whole lot less. We tried both nozzle on a Rogers just like yours and adjustable plates on a Hondo Pantera. The Pantera has a shallower V which made the plates more aggressive when you planted them for a turn. Plates work better when your off throttle since the jet uses thrust to adjust trim. Most people like to use a diverter (nozzle) to make a big roostertail, never understood that. For circle racing we set up the nozzle so at it's highest set (up) it made very little roostertail ( them's the rules now) plant your foot on the trim peddle and you went to full down. With throttle added you planted the bow. Technically in perfect water plates should slow you down. It's adding more hull behind the transom which is like moving the pump forward increasing wetted area and drag. In rough water it can help since you can add a bit of plate to lower the nose without getting so much off the gas.

Since it doesn't sound like your going to race this boat I would go with an adjustable nozzle. They are easy to install, cost less than adjustable plates, and people who know and love Rogers Boats won't think you listened to someone with marine knowledge that slowed down your boat.

I have no intention of racing it just would like to make it more usable until time and money allow me to get a bigger boat. I wasn't planning to spend the money I already have on it. It was purchased back in 06 for 6000.00 as a turn key beginner boat. For the first couple of years it was then the problems started showing up. Carburator, then ignition then pump and now the engine. Was going to just sell it with a blown motor but with this economy I wasn't going to get much or anything for it. Like all my old cars, I am kind of at the point of no return. I still don't see how a couple of plates would cost more than a diverter kit, but so far the experts are saying they are.

I think your having a hard time understanding the cost of a good (usefull) plate system. Theres alot more to it than just a couple plates. For a good (usefull) system you will need the plates, mounting blocks to mount the plates to the transom (or recess the bottom of the boat for the plates), turnbuckles, cross bars to tie all the turnbuckles together, the control rods that go through the hull, another cross bar to tie both sides together, another rod going up front, and finally a handle / pedal system, as well as LOTS of little parts along the way to make it all work. Lots of work and lots of money in parts. It will look something like this, but be two seperate smaller plates. With a good system (like above) you would be able to adjust the boats ride angle from the drivers seat. Plates down to drop the bow slow the boat and get it set for a turn, plates slightly up to let it fly. Not something a lake jet boat really needs unless its a bad hull design to start with, and yours is not a bad design.

A basic plate set up with no way to adjust in from the drivers seat. Is a pain in the azz and should only be added if the boat has issues that cant be solved with normal set up work (bad porpoising, etc). It will be set in one position and your stuck with that position.

Wow thanks for that post. The second picture is what I would have to do if I was to do it. It is a really shallow boat. No doubt it is a fast hull as in smooth water it would do 65 at 4400RPM with a very very tired engine. On the other hand if the water is the least bit rough you might as well park it. You can't get any speed going and it feels like it is going to break in half not to mention the people inside. Guess I will have to decide if I want to throw any more money at it and put a diverter on it. The sad thing is it really isn't worth much and I have spent much more than I had planned.

I think your having a hard time understanding the cost of a good (usefull) plate system. Theres alot more to it than just a couple plates. For a good (usefull) system you will need the plates, mounting blocks to mount the plates to the transom (or recess the bottom of the boat for the plates), turnbuckles, cross bars to tie all the turnbuckles together, the control rods that go through the hull, another cross bar to tie both sides together, another rod going up front, and finally a handle / pedal system, as well as LOTS of little parts along the way to make it all work. Lots of work and lots of money in parts. It will look something like this, but be two seperate smaller plates. With a good system (like above) you would be able to adjust the boats ride angle from the drivers seat. Plates down to drop the bow slow the boat and get it set for a turn, plates slightly up to let it fly. Not something a lake jet boat really needs unless its a bad hull design to start with, and yours is not a bad design.

A basic plate set up with no way to adjust in from the drivers seat. Is a pain in the azz and should only be added if the boat has issues that cant be solved with normal set up work (bad porpoising, etc). It will be set in one position and your stuck with that position.

Not trying to thread jack here, but what ever happened to the blue boat in the pictures? I know it sold